Ambipolar Conduction and Multicolor Photosensing Behaviors from Poly(9,9-di-n-octylfluorenyl-2,7-diyl)-Molybdenum Disulfide Heterointerfaces

Abstract Molybdenum disulfide (MoS2) in two-dimensional (2D) transition metal dichalcogenides (TMDs) has attracted attention as a next-generation semiconductor material owing to its intriguing electrical, optical, and mechanical characteristics, which enable its applications in flexible display backplane thin-film transistors, photodetectors, and complementary metal oxide semiconductor (CMOS) digital circuits. However, MoS2 films only have n-type operating characteristics, and p-type conduction in MoS2 devices has rarely been reported owing to their strong n-type semiconducting property. Herein, we demonstrate the p-doping effects in poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO)-MoS2 heterointerface. By simply coating PFO on the top of pre-fabricated MoS2 field effect transistors (FETs), the proposed PFO-MoS2 heterointerface devices could be implemented. A positive shift in the threshold voltage and reduction in the on-current were observed in the proposed PFO-MoS2 heterointerface devices, which indicated ambipolar characteristics with p- and n-type charge transport behaviors. More importantly, the multicolor photosensing behaviors by red, green, and blue light with enhanced sensitivity of PFO-MoS2 hetero-interfacial devices were enhanced.